102.5 to Spanish? Nahhh.....

[Scott Fybush]

>By my very rough measurements, The FM 128 tower is 10 miles from 
>dowtown Boston, while Andover is 20 miles.  This should mean that 
>both stations have a grade A signal downtown.  The biggest 
>difference should be that 99.5 would be weaker south of Boston, but 
>stronger into southern NH and ME.  I'm sure this was a consideration 
>in locating the country format there and moving the "smooth jazz" 
>(at the time) format to 96.9 so many years ago.
>
>Likewise, 102.5 should be stronger than 99.5 in areas west and south 
>of Boston.
>
>So, it all really has to do with the suburbs.  While Boston may be 
>considered the hub, the total population of the suburbs is several 
>times the population of the city.  By how much depends on how far 
>out you consider to be suburbs.  But it is clear to me that most 
>stations in the Boston market need to consider the suburban audience 
>more than the city audience if they are to maximize their listenership.

There are a few other pieces to this puzzle, too.

Merely having a "grade A" (which is really a TV term, not a radio 
term) signal downtown isn't enough anymore. To have any hope of being 
heard on a real-world radio in much of the city, you've got to be 
able to overcome the "RF haze" that blankets the city from the many 
FMs on the Pru. Realistically, that means not merely a 60 dBu 
(usable, absent other factors, by most home receivers) or a 70 dBu 
("city-grade") signal, but something more in the range of 80 dBu.

Using zip 02116, right in the Back Bay, as my measuring point, the 
calculator at www.v-soft.com tells me that the Pru FMs are putting 
about 122 dBu over the neighborhood. The FM128 FMs, WCRB included, 
clock in with 86 dBu or so.

Anyone who's driven through the Back Bay knows any signals less 
strong than those have problems - WFNX delivers 78.2 dBu, WMKK 
delivers 77.8, and even they experience trouble from the Pru.

The 99.5 signal delivers 68.7 mVm, which would be a great signal in 
most non-urban areas, but not so great in the RF-saturated 
neighborhoods of Boston.

Larry's correct that the difference between the two signals is 
dramatic north and south of Boston - Brockton, for instance, gets 
about 72 dBu from both the Pru and FM128 FMs, but only 53 dBu from 
WKLB, which is barely enough to provide adequate car-radio reception. 
Go up to Salem, N.H. and you get 83 dBu from WKLB, 61 dBu from the 
Pru and 59 dBu from FM128. I would bet that there's a decent audience 
for country music, if not in Brockton proper, then certainly in 
neighboring towns - and I'd bet many WKLB advertisers would take the 
tradeoff of somewhat weaker reception in southern NH to be able to 
reach the South Shore on 102.5.

(Worcester gets 61 dBu from FM128, 56 dBu from the Pru and 53 dBu from WKLB.)

There are other factors, too, especially with the introduction of HD 
Radio (and we know Greater's been a strong proponent of HD Radio). In 
a crowded spectrum like New England's, adjacent-channel interference 
can kill HD reception even in areas where the received signal is 
relatively strong. 99.5 gets severely pinched by WPLM on 99.1, making 
HD reception on that frequency iffy in Boston proper and impossible 
anywhere to the south. 102.5's edges are considerably cleaner. (This 
assumes, of course, that HD radios ever become widely available, but 
that's another discussion.)

s